This invention relates to a display device of a thin-film three-layered EL structure and more particularly a circuit and method for driving the display device for assuring legibility in a visual display and reliability of long-term operation.
A thin-film EL display panel includes an array of scan electrodes and an array of data electrodes crossing the scan electrodes in a normal direction and a number of EL pixels lying sandwiched between a respective one of the data electrodes and a respective one of the scan electrodes. After scanning is completed throughout the panel while a write pulse V.sub.W is applied sequentially to the scan electrodes in a line scanning fashion, a refresh pulse of an amplitude V.sub.R is applied to complete an alternating cycle of driving. Whether or not the respective pixels on the same scan electrodes are excited is determined by pre-charging of a modulation voltage V.sub.M and especially the pixels desired to be excited are supplied with a write voltage of V.sub.W +V.sub.M and those desired to be non-excited are supplied with a write voltage of V.sub.W -V.sub.M. This driving method is suggested by many patents assigned to the assignee of this application including, for example, U.S. Pat. Nos. 3,946,371 to K. Inazaki et al, 3,967,112 to Y. Kanatani et al, 4,024,389 to Y. Kanatani et al, 4,070,663 to Y. Kanatani et al, etc. With those suggested driving methods, a so-called burning phenomenon takes place where a fixed display pattern of figures and characters remains even return to the non-displayed state after the display panel has displayed the fixed display pattern for a substantial period of time.